JPS5650744A - Closed forging method making use of double-acting press - Google Patents

Abstract

PURPOSE: To thinly form the excess metal parts of the punch holes where no piping defects are produced, by interposing members for controlling the depth of the punch holes between the end faces of the upper and lower outer punches of a double-acting press and the end faces of the circumferential edge parts in the large diameter parts of the upper and lower inner punches.

CONSTITUTION: Spacers 20 which control the depth of the punch holes of a blank material are interposed between the end faces of the outer punches 13, 13' on the inner side of upper, lower dies 14, 15, and the end faces in the circumferential parts of the large-diameter parts 10 of inner punches 12, 12'. The spacers 20 are movable in the radial direction by fluid pressure cylinders 21. A blank material is inserted into the lower die 15, and is closed with the upper die 14. With the spacers 20 held inserted, the blank material is pressed by the upper and lower inner, outer punches 12, 12', 13, 13' to form the punch holes of thick excess metal. The pressing is then stopped and the spacers 20 are moved to the outer side, thence the upper and lower inner punches 12, 12' are pushed in. Thereby, the blank material is extruded in the height direction and the outer punches 13, 13' retreat and stop at the under surfaces in the large-diameter parts, thus the punch holes become thin and no piping defects are produced.

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